Numerous attempts have been made to formulate laundry detergent compositions that have good cleaning properties together with textile softening properties so as to avoid the necessity of using a separate rinse-added textile softener product in addition to the usual laundry detergent. Since cleaning by definition involves the removal of material from the textile surface and textile softening normally involves deposition of material onto the same surface, these attempts have typically required a compromise in formulation between cleaning and softening performance.
Cationic surfactants, including quaternary ammonium surfactants, have long been known as useful additives in laundry detergent compositions for the purpose of providing laundered fabrics with a static control benefit (see e.g. U.S. Pat. No. 3,951,879, Wixon, issued Apr.20, 1976, and U.S. Pat. No. 3,959, 157, Inamorato, issued May 25, 1976, both of which are incorporated herein by reference), a fabric softening benefit (see e.g., U.S. Pat. No. 3,607,763, Salmen et al, issued Sep. 21, 1971, U.S. Pat. No. 3,644,203, Lamberti et al, issued Feb. 22, 1972, and U.S. Pat. No. 3,537,993, Coward et al, issued Nov. 3, 1970, all of which are incorporated herein by reference), or a sanitization benefit (see e.g., U.S. Pat. No. 2,742,434, Kopp, issued Apr. 17, 1956, U.S. Pat. No. 3,539,520, Cantor et al, issued Nov. 10, 1970, and U.S. Pat. No. 3,965,026, Lancz, issued Jun. 22, 1976, all of which are incorporated herein by reference).
Attempts to formulate aqueous heavy duty liquid laundry detergent compositions containing anionic surfactants and a quaternary ammonium fabric-softening agent like lauryl trimethyl ammonium chloride and which provide softening through the wash and static control benefits have resulted in poor physical product characteristics including phase split or have resulted in poor fabric cleaning performance.
It has now been found that aqueous, heavy duty liquid detergent compositions containing certain anionic surfactants and a quaternary ammonium fabric-softening agent provide softening through the wash and antistatic benefits, excellent cleaning performance, and attractive product characteristics, i.e., are substantially clear, isotropic and phase stable. It has been found that by limiting the level of alkyl benzene sulfonates in aqueous, detergent compositions containing alkyl polyethoxylate sulfates, unsightly precipitates are prevented or inhibited from forming in the detergent product and superior performance (vis-a-vis cleaning, softening through the wash and antistatic benefits) is promoted.
Therefore, it is an object of the invention herein to provide a substantially clear, isotropic aqueous heavy duty liquid laundry detergent composition which provides excellent cleaning and softening through the wash and anti-static benefits.